Raising boost on a td5

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Originally Posted by JoeFriend

With the nanocom you can see what reading the MAF is giving out. Idle is 50-60 and you can see it go up from there. MAP will be shown in bar just so you know.

The issue is when you turn up the boost, you can easily go over the allowed 680 on your MAF. That is the point I am at and trying to figure a way around. I would prefer to not block the signal and limit the MAF to 650 as the ECU will then just fuel for that ratio, which of course it will actually be higher. I don't get the MIL light and fuel cut off, I just get reading of zero and default mapping.

Sent from my SM-G900I using AULRO mobile app

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1. MAP is shown in KPa in inputs fueling and that's more relevant, only ''turbo pressure'' is shown in Bar by nanocom on instrument mode but that's a calculated value which is not very accurate.

2. the MAF should not go over 680 if the sensor is good and there's no boost leak even if the wastegate is tightened cos at around 670 the MAP should reach the 242 overboost limit before that(unless there's a boost box fitted), so if the MAF goes above 680 without a boost box then something is wrong and needs investigation, usually '"tired" MAF or too high alternator output

3. the MIL can be triggered in only two cases , by throttle position sensor and crankshaft speed and position sensor complete failures, the MIL has nothing to do with MAF or MAP or other management components whatsoever(it will only flash on the purge sequence)

hope this helps

Ok, I will re-attach the MAP and disconnect the MAF and report back. I have printed off the nanocom 'hit-list' and going to see my man on Sunday and will report back after. If his machine is no good then I will try and find an aulro member who is local to Warrandyte. Getting there slowly, with thanks. My history was rebuilding Beetle engines (and other bits of Beetle's) with my RAF Engineer Uncle 20 years back in UK. Now going solo and loving having a vehicle I can work on and play with again. Other car is a turbo diesel VW Passat - say no more !!!!

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Originally Posted by sierrafery

1. MAP is shown in KPa in inputs fueling and that's more relevant, only ''turbo pressure'' is shown in Bar by nanocom on instrument mode but that's a calculated value which is not very accurate.

2. the MAF should not go over 680 if the sensor is good and there's no boost leak even if the wastegate is tightened cos at around 670 the MAP should reach the 242 overboost limit before that(unless there's a boost box fitted), so if the MAF goes above 680 without a boost box then something is wrong and needs investigation, usually '"tired" MAF or too high alternator output

3. the MIL can be triggered in only two cases , by throttle position sensor and crankshaft speed and position sensor complete failures, the MIL has nothing to do with MAF or MAP or other management components whatsoever(it will only flash on the purge sequence)

hope this helps

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Well, my brand new genuine MAF is going above 680 very quickly, so curious to figure out what the problem is there. Any ideas???

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How much are the AAP, MAP and voltage readings when this happens.... read MAP in inputs fuelling not boost in instruments mode, also does your MAF has Siemens stamp on it?, cos there are some fake so called OEM or genuine MAF's on the market


btw, do you have snorkel?

AAP is normal, around 103. Voltage maxes out at 14.4 or so from memory.

Will have to check the MAP when I drive next.

Yep, I have a snorkel - does that make a difference?

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So I reconnected the MAP and disconnected the MAF, first time I put my foot down when warm and the fuel limiter cut in. adjusted the waste gate back about 3 turns and improved. Power delivery much better. I the put foot down at 60 kms and got to 80 and pretty much stayed there, revving but not much else. Pulled over again and wound adjuster back a couple more turns. Seems better, will drive more tomorrow.

So at this point can I take the MAF needs a clean / replacing ? And also feeling a bit lost as to where the waste gate adjustment should be ? Will this all be resolved when get access to the Nanocom ?

adjust the wastegate rod as to count 10 threads left out from the locking nut and if it overboosts back one turn at a time untill it doesnt, if you get overboost at 13 threads left which is the standard setup it means the wastegate modulator is gone then unplug it, if it's not blocked closed it should be oprn unplugged so it will be like bypassed... off course that a nanocom session will reveal some issues if they are

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Originally Posted by JoeFriend

AAP is normal, around 103. Voltage maxes out at 14.4 or so from memory.

Will have to check the MAP when I drive next.

Yep, I have a snorkel - does that make a difference?

Sent from my SM-G900I using AULRO mobile app

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If the snorkel's intake is toward the front it might increase the flow at high speeds in some cases(i've seen a few) so make a test with it turned back to see if there's any difference or not.

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Originally Posted by sierrafery

If the snorkel's intake is toward the front it might increase the flow at high speeds in some cases(i've seen a few) so make a test with it turned back to see if there's any difference or not.

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I will give it a try when I drive on Thursday, I thought about it but figured that the ram effect cant be that big, and it seems to happen more when I put the right boot in.

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I wound back the adjustor to 10 threads and have left the MAF disconnected. Car running better, I have bought some contact cleaner, so not sure if I should clean the MAF unit or do anything now prior to getting hooked up on the nancom on Sunday ?


I will report back next week and thanks for help as always.